Producing a 20-inch gun barrel is only one part of building a ship around it. The navy also needs a mounting and stabilization system, along with docks, yards, and industrial capacity for a hull large enough to carry the weapon. The Bismarck class is presented as a product of German infrastructure and the legacy of Versailles. A proposed calibre means little until the wider shipbuilding system can produce and sustain the complete capital ship.
Notable Point · 1:56:36-1:58:32
Why a larger German gun needed more than a barrel
Germany's ability to make a very large gun would not by itself create a viable 20-inch-gun battleship.